Bioreactor for sewage and wastewater treatment

ABSTRACT

The present invention relates to a bioreactor for sewage and wastewater treatment, which is capable of agitating and supplying oxygen simultaneously. A bioreactor of the present invention, comprises a culture drum in which microorganisms are cultured; a supplier for supplying a culture solution, and organic and inorganic media to the culture drum, the supplier including a supply tube connected to an upper side of the culture drum, and a pump connected to the supply tube for supplying the culture solution to the culture drum; an agitator for agitating the culture solution by spraying air into the culture solution in the culture drum, the air being supplied from an air blower; and a thermostatic controller for controlling a temperature of the culture solution and disinfecting the interior of the culture drum.

BACKGROUND OF THE INVENTION

(a) Field of the invention

The present invention relates to a reactor for culturing microorganismused for treating sewage and wastewater, and more particularly to abioreactor for sewage and wastewater treatment, in which the bioreactoris capable of agitating and supplying oxygen simultaneously.

(b) Description of the Related Art

Generally, methods of treating wastewater include a physical-chemicalmethod and a biological method. The drawbacks of the physical-chemicalmethod include high costs and the need to re-treat the products, whilethe biological method produces a relatively little amount of productafter treatment by resolving a large amount of organism elements intocarbon dioxide to be stabilized, or by removing organic matterscontained in wastewater with the generation of methane gas.

In the biological treatment method, pollutants in wastewater can beresolved, detoxified, and separated by using mainly microorganisms.Hence, the method is applied to treat industrial sewage containingorganic matter and sludge generated therefrom, and to secondarily treatlife sewage. Due to the relatively low cost and the variations of workprogress, the biological method has been most widely used all over theworld.

Microorganisms that play a core role in biological treatment are mixedcultures including various microorganism populations such as bacteria,fungi, protozoa, and metazoa, which are cultured and multiplied in abioreactor. Such microorganisms cleanse sewage and wastewater byresolving and removing organic pollutants, which nourish themicroorganisms, while the microorganisms multiply using oxygen dissolvedin wastewater.

The bioreactor is a device that provides conditions similar to thosefound in nature to allow facultative microorganisms to be efficientlycultured. The bioreactor supplies a culture solution, organic andinorganic media, and air to the inside of the bioreactor, and culturesand multiplies the microorganisms.

Since the bioreactor is directly related to the culture andmultiplication of microorganisms, the efficiency of sewage andwastewater treatment or the activation state of microorganisms dependson the bioreactor.

As a prior art method to enhance the efficiency of sewage and wastewatertreatment by employing a bioreactor, published PCT Application WO96/15992 discloses a method of treating sewage by injecting four typesof aerobic and anaerobic microorganisms into an aeration tank withoutexhausting unpleasant odors, noxious gases, and toxic substances.

However, the above-described method is not used to multiplymicroorganisms in the aeration tank, and instead is used for removingnoxious gases, etc. by applying specific microorganisms obtained fromnature to the sewage sludge. A drawback of the method is that it takeslong time for the injected microorganisms to treat the sludge.

U.S. Pat. No. 5,376,275 discloses an activated sludge treatment process,wherein a sewage sludge component is fermented for a period of at least15 days to form soluble carbonaceous substrates, the fermented sludgecomponent is contacted with influent sewage to form a conditionedsewage, and the conditioned sewage is supplied to the activated sludgeplant.

However, the above-described process is not used for multiplyingmicroorganisms in the fermentation plant, and instead is used for thedephosporization and denitrification of the sludge by usingmicroorganisms. This method also has the drawback that it takes longtime, for example, from 15 days to 60 days, to treat the sludge.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a bioreactor forsewage and wastewater treatment which is capable of agitating andsupplying oxygen simultaneously.

It is still yet another object of the present invention to provide abioreactor for sewage and wastewater treatment which is capable ofaccomplishing disinfection and culture through a swift change oftemperature.

It is still yet another object of the present invention to provide abioreactor for sewage and wastewater treatment which is capable ofminimizing heat efflux.

It is still yet another object of the present invention to provide abioreactor for sewage and wastewater treatment which is capable ofbringing an aeration solution of an external wastewater disposal plantinto the bioreactor to ease the culture of microorganisms.

It is still yet another object of the present invention to provide abioreactor for sewage and wastewater treatment which is capable ofeasily activating the microorganisms.

In order to achieve the objects, a bioreactor according to a preferredembodiment of the present invention includes a culture drum in whichmicroorganisms are cultured; a supplier for supplying a culturesolution, and organic and inorganic media to the culture drum; and anagitator for agitating the culture solution while injecting air into theculture drum.

The present invention further includes a thermostatic controllerprovided in the culture drum, the thermostatic controller being forcontrolling a temperature of the culture solution.

The supplier includes a supply tube connected to an upper side of theculture drum, and a pump for supplying the culture solution to theculture drum, the pump being connected to the supply tube. The suppliermay also include a valve for opening and shutting the supply tube, and apressure gauge.

The agitator includes an air blower for air supply, an injection pipeprovided in the culture drum for injecting the air supplied from the airblower to the culture drum, and an injection nozzle arranged on theinjection pipe in a predetermined direction for circulating the culturesolution in the culture drum.

The thermostatic controller includes a low temperature heater and a hightemperature heater provided in the culture drum, and a heatercontroller.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention, and many of the attendantadvantages thereof, will be readily apparent as the same becomes betterunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic view of a bioreactor according to a preferredembodiment of the present invention.

FIG. 2 is a plan view of the bioreactor of FIG. 1.

FIG. 3 is a schematic sectional view of the bioreactor of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following detailed description, only the preferred embodiment ofthe invention has been shown and described, simply by way ofillustration of the best mode contemplated by the inventors of carryingout the invention.

FIG. 1 is a schematic view of a bioreactor according to a preferredembodiment of the present invention, FIG. 2 is a plan view of thebioreactor, and FIG. 3 is a schematic sectional view of the bioreactor.

Referring to FIGS. 1 through 3, a bioreactor according to a preferredembodiment of the present invention comprises a culture drum 20vertically provided on a base frame 10 in the shape of a cylinder, asupply tube 30 connected to an upper side of the culture drum forinjecting a culture solution into the culture drum 20, a pump 31provided on the base frame 10 and connected to the supply tube 30 fortransferring the culture solution through the supply tube 30, an airblower 40 provided on the base frame 10 for air supply, an air supplyhose 41 connected to the air blower 40 for transfer of air therethrough,injection pipes 60 and 61 connected to the air supply hose 41 at avertically predetermined interval inside the culture drum 20, theinjection pipe 60 having a ring shape, injection nozzles 62 and 63arranged along outer circumferences of the injection pipes 60 and 61 atan angle of a predetermined angle for agitating the culture solution, alow temperature heater 50 provided inside the culture drum 20 forheating the culture solution, a high temperature heater 51 providedinside the culture drum 20 for disinfecting the inside of the culturedrum 20 at a high temperature after discharging the culture solution,and a heater controller 52.

To the overall outer surface of the culture drum 20 is attached a heatshield material 25 such as polyurethane. The culture drum 20 is providedwith an inlet 21 on the upper side thereof for supplying culture mediaetc., and the inlet 21 is provided with a cover 22 for closing the inlet21.

A level gauge 23 provided to the outer side of the culture drum 20. Thelevel gauge 23 is a transparent tube that is vertically arranged toallow the water level in the culture drum 20 to be visually verified. Athermometer (not shown) is provided to a side of the culture drum 20 forobserving the temperature of the culture solution, and a discharge tube24 is provided to the bottom of the culture drum 20 for discharging theculture solution that has been cultured.

The pump 31 is fixedly provided on the base frame 10, and is connectedto an aeration tank of a wastewater treatment plant, which is locatedoutside the culture drum 20, through the supply tube 30. The pump 31draws an aeration solution, etc. from the wastewater treatment plant,and injects the aeration solution, etc. into the culture drum 20 throughthe supply tube 30 connected to the upper side of the culture drum 20.In addition, a pressure gauge 32 is provided to a side of the supplytube 30.

The air blower 40 is fixedly provided to a side of the base frame 10.The air supply hose 41 connected to the air blower 40 includes an airfilter 42 on an end thereof. The air filter 42 filters out impuritiescontained in the air then supplies the fresh air, which is required as acondition for culturing, to the culture solution. A solenoid valve 43 isprovided to the air supply hose 41, the solenoid valve 43 being locatedbefore and behind the air filter 42.

The air supply hose 41 is vertically mounted along the sidewall of theculture drum 20, and branch lines 43 and 44 are extended from the lowerend and the part above the lower end of the air supply hose 41,respectively, to the inside of the culture drum 20 through the sidewallof the culture drum 20. The injection pipes 60 and 61, which has ringshape, are provided at the end of each of the branch lines 43 and 44.

The injection pipes 60 and 61 are located at the center of the culturedrum 20 at a predetermined distance from the inner wall of the culturedrum 20, and supported by connecting an end thereof with the end of thebranch lines 43 and 44. Alternatively, the injection pipes 60 and 61 maybe supported by providing a connecting tube that crosses the center ofthe injection pipes 60 and 61, and by connecting the connecting tube tothe branch lines 60 and 61 that are introduced into the culture drum 20and bent downward at the center of the culture drum 20. In this case,the air would be transferred to the injection pipes 60 and 61 via theair supply hose 41 and the branch lines 43 and 44 through the connectingtube.

A solenoid valve 45 is provided on each of the branch lines 43 and 44that are extended from the air supply hose 41. The solenoid valves 45open and close each of the branch lines 43 and 44.

The low temperature heater 50 is used to ensure an optimum temperatureof the culture solution, a change in the physical properties of theculture solution, and the effective conditions of the culture solution.The surface temperature of the low temperature heater 50 is raised toless than about 60° C. The high temperature heater 51 is used fordisinfection. The surface temperature of the high temperature heater 51is raised to more than about 60° C.

The above two heaters 50 and 51 are provided in the culture drum 20 at apredetermined interval, and are supplied with electric power by theheater controller 52 provided on the outer surface of the culture drum20.

The heater controller 52 supplies electric power to a hot wire of thelow temperature heater 50 so as to satisfy the effective cultureconditions of the culture solution, and can maintain the temperature ofthe culture solution at an optimum level.

The injection nozzles 62 and 63 provided on the injection pipes 60 and61, respectively; mix the culture solution by supplying air to theculture solution and controlling the direction of the injected air. Asshown in FIG. 3, a plurality of injection nozzles 62 is located at theouter surface of the upper injection pipe 60. The injection nozzles 62extend from the outward direction to the downward direction along theouter circumference of the ring-shaped injection pipe 60. Also, aplurality of injection nozzles 63 is located at the outer surface of thelower injection pipe 61. The injection nozzles 63 extend from the inwarddirection to the upward direction along the outer circumference of thering-shaped injection pipe 61.

Since each of the injection nozzles 62 and 63 provided to the upper andlower injection pipes 60 and 61 are formed at a predetermined angle witheach other, the culture solution is raised at the interior of theinjection pipes 60 and 61 and lowered at the exterior of the injectionpipes 60 and 61, and thus is circulated by the air injected from theinjection nozzles 62 and 63. During the above process, the culturesolution can be mixed sufficiently.

An operation of the present invention will now be described.

A solution including microorganisms intended for culturing istransferred to the culture drum 20 through the supply tube 30 by thepump 31. The quantity of the supplied culture solution can be determinedby observing the level gauge 23 provided to the sidewall of the culturedrum 20.

When the optimum quantity of the culture solution in the culture drum 20has been reached, operation of the pump 31 is discontinued and theculture solution is heated to a predetermined temperature by supplyingelectric power to the low temperature heater 50.

Since the low temperature heater 50 is provided inside the culture drum20, and thus is immersed in the culture solution, the heat generatedfrom the heater 50 can be directly transferred to the culture solutionso as to heat the culture solution to an optimum temperature.

The low temperature heater 50 can maintain the culture solution at apredetermined temperature (about 25±5° C.), while the surfacetemperature of the heater 50 is kept at a predetermined level (usually30±10° C.) by the heater controller 52.

Culture media together with the culture solution are supplied into theculture drum 20 through the inlet 21 provided on the upper side of theculture drum 20 so as to activate culturing.

The culture solution is mixed with the culture media, and the mixturesupplies the cultured microorganism with oxygen. The culture can beactivated as a result.

The air blower 40 supplies air to each of the branch lines 43 and 44through the air supply hose 41. The supplied air is transferred to theinjection pipes 60 and 61 connected to the branch lines 43 and 44,respectively, and is finally sprayed to the culture solution through theinjection nozzle 62 and 63 arranged along the outer circumference of theinjection pipes 60 and 61, respectively.

The air through the injection nozzle 62 that is provided to the upperinjection pipe 60 is sprayed in the directions ranging from the downwardand outward directions of the ring-shaped injection pipe 60, so that theculture solution flows downward with the sprayed air.

On the other hand, the air through the injection nozzle 63 that isprovided to the lower injection pipe 61 is sprayed in the directionsranging from the upward and inward directions of the ring-shapedinjection pipe 61, so that the culture solution flows upward passingthrough the center of the injection pipe 61 with the sprayed air.

Therefore, the culture solution flows downward between the upperinjection pipe 60 and the inner wall of the culture drum 20, then flowsupward passing through the center of the lower injection pipe 61 by theinjection nozzles 62 and 63, and thus the culture solution cancirculate. During the above process, the culture solution and theculture media are mixed uniformly, and the supplied oxygen can betransferred uniformly to the microorganisms.

Accordingly, a bioreactor of the present invention is capable ofagitating the culture solution and supplying oxygen theretosimultaneously by the injected air, without the use of an additionalagitator.

After the culture has been completed, the culture solution is dischargedthrough opening of the discharging tube 24 provided on the bottom of theculture drum 20, and the interior of the culture drum 20 is disinfectedunder high temperature conditions by operation of the high temperatureheater 51. The interior of the culture drum 20 is rapidly heated anddisinfected at a temperature used for this operation (about 95±5° C.) byoperation of the high temperature heater 51.

The case where a bioreactor of the present invention is practicallyapplied to wastewater treatment is described as follows.

Aeration solution of an aeration tank is directly introduced to theculture drum 20 through the supply tube 30, then microorganisms aremixed with the aeration solution under the same conditions as in theabove.

Such microorganisms are supplied to wastewater through the injectionnozzles 62 and 63 of the injection pipes 60 and 61. The microorganismscleanse the sewage and wastewater by resolving and removing organicpollutants, which nourish the microorganisms, while the microorganismsare multiplied by using oxygen dissolved in wastewater.

The bioreactor according to the preferred embodiment of the presentinvention can easily culture the microorganisms by introducing thesolution intended for culturing from the outside.

Further, the bioreactor according to the preferred embodiment of thepresent invention can increase the efficiency of wastewater treatment bydirectly culturing the aeration solution of the aeration tank.

The bioreactor according to the preferred embodiment of the presentinvention can also simplify structure by stirring the culture solutionby the oxygen supplied into the culture drum without the use of anadditional agitator.

While the present invention has been described in detail with referenceto the preferred embodiments, those skilled in the art will appreciatethat various modifications and substitutions can be made thereto withoutdeparting from the spirit and scope of the present invention as setforth in the appended claims.

1. A bioreactor comprising: a culture drum in which microorganisms arecultured; a supplier for supplying a culture solution, and organic andinorganic media to the culture drum, the supplier including a supplytube connected to an upper side of the culture drum, and a pumpconnected to the supply tube for supplying the culture solution to theculture drum; an agitator for agitating the culture solution by sprayingair to the culture solution in the culture drum, the air being suppliedfrom an air blower, wherein the sprayed air provides a controlledcirculation pattern for the culture solution; and a thermostaticcontroller for controlling a temperature of the culture solution anddisinfecting the interior of the culture drum, the thermostaticcontroller including at least a heater provided in the culture drum, anda heater controller; wherein the agitator includes an air supply hosewhich is vertically provided along the sidewall of the culture drum andconnected to the air blower; two branch lines which are extended fromthe air supply hose to the inside of the culture drum through thesidewall of the culture drum; an upper and a lower ring-shaped injectionpipe which are provided at the end of the branch lines; a first group ofinjection nozzles which are located at the outer surface of the upperinjection pipe, and are extended from the outward direction to thedownward direction along the outer circumference of the ring-shapedinjection pipe; and a second group of injection nozzles which arelocated at the outer surface of the lower injection pipe, and areextended from the inward direction to the upward direction along theouter circumference of the ring-shaped injection pipe.
 2. The bioreactorof claim 1, wherein a heat shield material is attached to the outersurface of the culture drum.
 3. The bioreactor of claim 1, wherein thethermostatic controller includes a low temperature heater for effectinga temperature condition needed for culturing by being heated to lessthan 60° C., and a high temperature heater for disinfecting the culturesolution by being heated to more than 60° C.
 4. The bioreactor of claim2, wherein the heat shield material is polyurethane.
 5. The bioreactorof claim 1, wherein the controlled circulation pattern includes therising of the culture solution in the center of the culture drum andlowering of the culture solution near the walls of the culture drum.